Water ski tow-rope attachment



A ril 16, 1963 M. NORTHRUP WATER SKI TOW-ROPE ATTACHMENT Filed April 22, 1960 LYLE M. NORTHRUP INVENTOR.

BY A TO NEY United States Patent 3,085,542 WATER SKI TOW-ROPE ATTACHMENT Lyle M. Northrup, 711 Decorah Ave., Decorah, Iowa Filed Apr. 22, 1960, Ser. No. 24,095 1 Claim. (Cl. 114-235) The present inventio ri relates to a water ski tp w rppe retire mentanhue.

bb a rd motor. More particularly it relates to an improved flexible attachment which reduces the torsional and binding stress applied to the mounting housing and which at the same time is universally adaptable to all outboard motors.

In the past, it has been proposed to mount a water-ski tow rope attachment to the lower drive shaft housing of an outboard motor. These attachments have been made of two cast metal or of preformed steel members which, when placed together, have the peripheral shape of the housing. A rigid ring is carried on one end of the attachment to which a tow rope for pulling water-skiers is attached.

Because of their rigidity, the metal castings or preformed metal members tend to bite and dig into localized areas of the lower housing when torsional stresses are applied by the jerking and waving action of a water-skier. As a result, in many cases the housing gradually weakens and eventually cracks.

It is qsferw primarmhlect 9 this IQPtQ' vrde"' a w ter skito ope,.attachriieiifftiifigojiiiting on, a ,WWQE 95 x21... ill mwhichwis. supple, limber and Bram and prevents localized stresses from causing such housings to break.

A further object of the invention is to provide a waterski tow rope attachment having a pivotal ring to which the tow rope is connected for further reducing torsional stresses applied to the housing.

A. still further object of the invention is to provide a water-ski tow attachment which universally fits all outboard motors.

A still further object of the invention is to provide a water-ski tow attachment which will not scratch or mar an outboard housing and which is easy to install.

Other objects and advantages of the invention will become apparent from the following description and the accompanying drawings:

In the drawings:

FIG. 1 is a side elevational view of an outboard motor with the water-ski tow attachment of the invention on the drive shaft housing thereof.

FIG. 2 is a sectional view taken along lines 2--2 of FIG. 1 and,

FIG. 3 is an enlarged fragmentary side view of the pivoting ring clamp of the attachment.

Referring now to the drawings, there is shown in FIG. 1 a conventional outboard motor 10 having the motor indicated at 11, the drive shaft housing indicated at 12, the propeller housing indicated at 13 and the pivotal mounting clamp indicated at 14.

The water-ski tow attachment of the invention is shown at 15 mounted on the drive-shaft housing 12 above the water level 16. Such attachment comprises a pliant supple belt 17 and a clamping ring 18 (FIG. 2). According to the invention, the belt must be very limber and lithe to enable it to easily conform to the peripheral contour or shape of the drive shaft housing. For this purpose, it has been found that nylon belting approximately 2 inches wide and inch thick, having a test strength of approximately 4000 pounds is very suitable. Obviously, other types of equivalent belting may also be used.

The ring clamp 18 includes a pair of flat bars or plates 19 spaced apart in face to face relation as at 20. A ring 21 is formed by welding a continuous piece of round stock steel to the respective back faces 22 of the bars 19. In a preferred embodiment, the bars are 2 inches long, 1 inch wide and Y inch thick and the ring is of inch diameter round steel.

The bars extend vertically parallel to the length of the housing 12. The ring 21 defining an opening 23 therein is disposed in a substantially horizontal plane and is adapted to hold the ski tow rope as shown by the dotted line 23' of FIG. 1. Bolts 24 pass through the bars and draw them into clamping engagement with the belting as will be described below.

In installing the attachment, holes are initially formed in at least one end 25 of the belting. The belting is then encircled around the housing with the end 25 and the other end 26 thereof extending beyond and rearwardly of the housings trailing edge 27.

The belt ends are then passed between the bars and the unpunched end 26 marked for punching so that the leading edges 28 of the bars are held as tightly as possible toward the housings trailing edge 27 Holes 29 are then punched in the belt end 26 and both belt ends are then inserted between the bars for clamping by means of the bolts 24.

With the bar edges 28 gripping against the belt adjacent to the housing trailing edge 27, the belt is held extremely tight in skin-tight conformity with the housing. As a more important feature, the bars 19 and ring are able to pivot as a unit about a vertical axis at their bearing point adjacent the housing as shown by the dotted line position 30 in FIG. 2.

This pivoting action of the ring about a vertical axis prevents torsional shock loads from being applied to the housing as a skier weaves back and forth behind the boat. At the same time, because of the suppleness of the belting the ring can also turn or give" slightly about a horizontal axis further reducing the shock and torsional stresses which normally are imparted when a metal band or ring is used around the housing.

Moreover, by virtue of the non-metallic supple characteristics of the belt itself, the binding and digging tendencies norm'ally inherent in metal castings or straps are eliminated. Thus any stresses applied to the belt as it is pivoted are more evenly distributed around the periph cry of the housing. Further the metal bars are always spaced from direct contact with the housing by the belting.

The present invention also has the additional important advantage of being universally adaptable to all motors. Since the belt is very lithe, it can mold to any housing shape. On the contrary, where metal castings or preformed metal straps are used, it is necessary that a separate model be made for each outboard housing contour or shape.

While one form of belting and type of ring book have been described, it is evident that other types and shapes may be used without departing from the concept of the invention and the following claim.

I claim:

latetslsit w...etaellmentfgry un on the i e. shaft hous; g of an gptboardmptorbetweeiiftliem'oto r; glthet rerzeller. sh t heiress...@srefiaam ris a non-metallic member for encircling a drive shaft hoiisirig, said member being supple, flexible and pliant so that it will take the shape of the drive shaft housing and distribute the load of a water skier evenly over its contact area with said housing without cutting into said housing and applying localized stresses thereto; holding means connected to the member to hold it in tight contact with the said drive shaft housing'ti ml.a,ring hgy ing an gpe ning therein through which a ski tow rope may be -att e P remember and" positioned to p the rear ach d c rn drive shaft housing; said ring being held on said member for pivotal movement about a vertical axis and for yield- 'able movement about a horizontal axis to reduce the transmission of shock and torsional loads to said motor housing as a water skier takes various devious paths behind said motor.

References Cited in the file of this patent Re. 24,511 I 2,725,207 2,872,141

UNITED STATES PATENTS Hefner Feb. 3, 1959 

